Drugs Cause About Five Times More Side Effects Than We Realized

There's always that part at the end of drug commercials that goes something like: if you develop sausage fingers, webbed feet, or a three-week erection, call your doctor! But as exhaustive as those auctioneer-style lists sound, they barely scratch the surface when it comes to the side effects pople are actually experiencing.

Stanford researchers created an algorithm that identified 1,332 drug side effects not currently listed on labels. They estimate that each drug has 329 adverse reactions on average, nearly five times the 69 currently listed.

The FDA maintains a database of about 4 million side effects reported by doctors and patients, but no one's sure exactly what causes most of them. That's partly because so many people take more than one drug at a time—seniors take an average of seven—and it's impossible to know how all of the combinations react in each individual. It's also because individuals often react differently to the same drugs.

So researchers at the Stanford University School of Medicine wrote an algorithm that sifts through millions of reports and surfaces what they call "true" side-effects. They reported their new method in Science Translational Medicine.

One important adverse interaction they turned up was that serotonin reuptake inhibitors (SSRIs), which are antidepressants, interact badly with common blood pressure medications, diuretics called thiazides, significantly increase the risk of a heart condition called prolonged QT, which can lead to irregular heartbeats and sudden death.

But the FDA can't just slap this information on labels now. They have to do follow-up research, possibly a clinical trial examining people who take both SSRIs and blood pressure meds, to monitor them for prolonged QT. And what to do with the information on the thousands of side effects in this new database? Looks like the FDA's job just got even harder. [Nature News]